1. EF with simple multi-particle states Vishnu V. Zutshi NIU/NICADD

2. Hadron Position Resolution Since Eflow invariably involves associating clusters near an extrapolated track … How to do this in a digital calorimeter ? Study this using charged pions Resolution is defined w.r.t. the MC extrapolated position

3. 10 GeV charged pions Density weighted Energy weighted unweighted

4. 10 GeV charged pions

5. “Density” Need a hierarchy in the absence of an energy measurement Clumpiness of the surrounding A simple-minded realization of this used here: d i =  (1/dR ij ) where dR ij is the angular distance between cell ‘i’ and cell ‘j’

6. 10 GeV   unweighted Density weighted Measured relative to the energy weighted resolutions Cell area at first layer=0.64cm 2 Thanks Ben

7. 10 GeV   Measured relative to the energy weighted resolutions Cell area at first layer=4cm 2 Density weighted unweighted

8. 10 GeV   Measured relative to the energy weighted resolutions Cell area at first layer=6cm 2 Density weighted unweighted

9. 10 GeV   Measured relative to the energy weighted resolutions Cell area at first layer=9cm 2 Density weighted unweighted

10. 10 GeV   Measured relative to the energy weighted resolutions Cell area at first layer=12cm 2 Density weighted unweighted

11. 10 GeV   Measured relative to the energy weighted resolutions Cell area at first layer=16cm 2 Density weighted unweighted

12. 2GeV Photons maxima

13. Clustering Local ‘density’ maxima chosen as seed clusters Membership of each cell in the seed clusters decided with a distance function Calculate centroids Iterate steps 2 and 3 till distortion is below some threshold Could be unique or shared

14. Parameters Cell thresholds How many layers to lump together Neighborhood for maxima search Minimum no. of layers hit Neighborhood for membership Proto-cluster definition Uniqueness of membership

15. 10 GeV  0 High asymmetry Density weighted 

16. 10 GeV  0 Medium asymmetry Density weighted 

17. 10 GeV  0 Low asymmetry Density weighted 

18. 10 GeV  0 Low asymmetry Density weighted 

19. 10 GeV  0 Recon. energy Recon. mass 18%

20. 10 GeV  0 Recon. energy Recon. mass

21. Energy asymmetry A = abs(E  – E  )/(E  + E  )

22.     p   p  Density weighted 

23.     p   p Density weighted 

24.     p   E/Egen Eflow Cal only

25.     n   EMCal HCal  n 

26.     n   EMCal HCal n p

27.     n   recE (  ) genE (  ) Not reliable due to noncompensation

28.     n   Get the e/pi for the SD detector Scale the MC truth with that function Take the ratio of the reconstructed pion energy with the scaled MC truth This should have a mean of 1.0 (with an atrocious resolution) if things are working ok

29.     n  

30. Summary/Outlook A first pass clustering/track association algorithm exists applicable to EM/HAD, both analog/digital Encouraging results for multiparticle events More detailed study to expand and enhance (for instance particle id) Move to jets Feedback into calorimeter design